The individual compound N,N-bis(2-hydroxyethyl)-4-toluidine is known. In J. Org. Chem. 26 (1961) 1477-1480 it is disclosed that it can be prepared by reacting 4-toluidine with 2 mol of ethylene oxide and then purified for example by distillation or crystallization. N,N-Bis(2-hydroxyethyl)-4-toluidine is obtained there in a yield of 76% of theory.
In Inorg. Chemie Acta 1995, 240, 257-62 as well the preparation of N,N-bis(2-hydroxyethyl)-4-substituted benzenes is described. N,N-Bis(2-hydroxyethyl)-4-toluidine is prepared by reacting 4-toluidine with 2-chloroethanol. Also described is the preparation of the individual compound N-(4-methylphenyl)azatetraglycol
by reaction of 4-toluidine with 2-(2-chloroethoxy)ethanol.
EP-A-1 256 615 discloses two-component adhesive compositions comprising an adhesive component and an activator component. Included in the adhesive component alongside the acrylic-/methacrylic-based monomers are reducing agents, which are optionally substituted anilines or optionally substituted toluidines. Substituted toluidines described are generally those of the formula
in which R′ and R″ can be identical or different and by reference to previous definitions can denote among other things CH2CHY2, in which Y, among numerous other definitions, can also be OCnH2n+1 with n less than 4. The sole explicit example of a correspondingly substituted para-toluidine is the individual substance N,N-bis(2-hydroxyethyl)-p-toluidine mentioned in Example 4 (“Emery 5710” from Cognis Corporation).
From WO-A-00/43425 it is known that N,N-bis(2-hydroxyethyl)-4-toluidine can be used as an accelerator for polymerizations or vulcanizations. Described therein is a redox initiator system for producing polyester granules by suspension polymerization, this redox initiator system comprising a diacyl peroxide and an aromatic amine of the formula
in which Ar is an optionally substituted aryl group and R1 and R2 are given a general definition and among other things can each be —(CHR′CHR′—O)nH with n=1-10 and R′ being H or C1-3 alkyl. The preparation of commercially unavailable aromatic amines with polyoxyalkylene substituents on the nitrogen by reaction of the hydroxyalkyl compound with an alkylene oxide is said to be familiar to the skilled person. The sole explicitly cited substituted para-toluidine, which is also referred to as preferred, is, again, the individual substance N,N-bis(2-hydroxyethyl)-p-toluidine.
EP-A-1 070 730 describes how accelerators can be added for the rapid curing of methacrylate-based polymers. Condensation products of para-toluidine and ethylene oxide are specified for this purpose. Described explicitly is the product “Bisomer PTE” (International Specialty Chemicals), for which it is reported that two ethylene oxide units are located on each of the free valencies of the nitrogen.
US 2003/0083443 A1 discloses stabilized unsaturated polymer resin systems comprising a tertiary aromatic amine as vulcanization accelerator. The broad definition of the tertiary aromatic amine also embraces, on combination of the definitions of a very wide variety of substituents, tertiary aromatic amines having polyoxyalkylene substituents with 1-6 repeating oxyalkylene units on the nitrogen. Vulcanization accelerators specified as being preferred, however, are those which possess 3 different substituents on the nitrogen, of which only one is potentially a polyoxyalkylene substituent (paragraphs [0019] and [0026]). Here again, the sole substituted para-toluidine explicitly mentioned in the description is the individual substance N,N-bis(2-hydroxyethyl)-p-toluidine (paragraph [0075]). Furthermore, in Example 4, the product “Bisomer PTE” from International Speciality Chemicals is mentioned.
Chemia Stosowana 32, 3-4, 503-514 (1988) discloses the preparation of polyethoxylates of 4-alkylphenylamines by reaction of 4-alkylphenylamines with ethylene oxide in the presence of potassium hydroxide, a preparation which is investigated using as examples 4-hexyl-, 4-octyl-, 4-decyl-, 4-dodecyl- and 4-hexadecylphenylamine.
The object of the present invention was to provide a process by which further new N,N-bis(2-hydroxyalkyl)-4-toluidine derivatives can be obtained that can likewise be employed as polymerization accelerators or vulcanization accelerators.